I've only tested it in Chrome on Linux TBH, and I hadn't looked at developing these extensions before a couple of days ago, so maybe I messed something up... hope not!
I guess you might be able to make a similar JSON API available for so people could get your info about accounts, and we could document them in the same place? Then myself or other developers could enhance their extensions with this info.
Depending on how you did this, I could actually take them periodically and see whether they'd be useful as inputs to the classification too.